An automotive catalytic converter is an emissions control device that may be incorporated into the exhaust system of a motor vehicle between the exhaust manifold and the muffler. The catalytic converter contains one or more catalysts, such as those based on platinum, palladium, or rhodium, that reduce the levels of hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx) in the exhaust gas, thereby reducing the amount of these pollutants which would otherwise be emitted into the atmosphere from the vehicle. In a typical commercial catalytic converter, HC and CO in the exhaust are oxidized to form carbon dioxide (CO2) and water, and NOx are reduced to nitrogen (N2).
As a result of recent regulatory initiatives, motor vehicle emissions control devices, including catalytic converters, are now required to have longer useful lives. US regulatory authorities such as the US Environmental Protection Agency (EPA) and the California Air Resources Board (CARB) now require automotive emission control elements to function up to 150,000 vehicle miles. This requirement, coupled with tighter emission standards, places severe demands on catalytic converters and other exhaust emissions control devices. Catalytic converters lose efficiency primarily by two mechanisms. High exhaust temperatures can cause thermal damage, and a number of components introduced into the typical automotive internal combustion engine exhaust, e.g. from the lubricating oil, can act as poisons to the catalyst present in the converter.
In order to accommodate these stringent EPA requirements, it is important to develop methods for accelerated aging that adequately simulate the impact of various engine operating modes, and various oil components. A method is needed to simulate the consumption of the volatile components of oil in order to adequately and efficiently assess the impact of such consumption on the aging of a catalytic converter.